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General Wave Properties. Taken from ed links. What is a wave?. A wave is a transfer of energy from one point to another via a traveling disturbance A wave is characterized by its wavelength, frequency, and amplitude. Transverse . Waves that travel perpendicular to the direction of motion

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General Wave Properties

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What is a wave?

A wave is a transfer of energy from one point to another via a traveling disturbance

A wave is characterized by its wavelength, frequency, and amplitude

Transverse

Waves that travel perpendicular to the direction of motion

Examples: Light, -p wavesfor earthquakes, Ocean waves

Longitudinal

Waves that travel parallel to the direction of motion

Made up of compressions and rarefactions in the medium that they are traveling in

Examples: sound waves and s waves for earthquakes

Do You See The Difference Between Transverse And Longitudinal Waves?

Wavelength (λ)

Distance from successive crest to crest or trough to trough

Measured in meters

Frequency

Number of crests passing by per second

Measured in Hertz (Hz) defined to be one cycle per sec

Equal to the inverse of the amount of time it takes one wavelength to pass by

Amplitude

Maximum displacement of the wave

The amplitude will have different units depending on the type of wave

In a sketch of the wave, it is the distance from the middle of the wave to the peak

Wave Speed

Traveling Waves move through space at a certain speed

Where,

v is the speed of the wave (m/s)

λis the wavelength in meters (m)

f is the frequency in Hertz (cycle/s)

Matter / Quantum Waves

Electrons and other tiny particlesshow wave-like properties

A particle moving close to the speed of light (c) can diffract or bend around the edges of objects

Also, particles do exhibit interference which is a wavelike property

Any moving matter has wave characteristics in theory BUT the wavelength of any life-size particle, like a golf ball, is so small that it is negligible

To learn about matter waves in depth go on to the next slide; if not click

If we can sometimes consider an electron to be a wave, what is its wavelength?

Its wavelength depends on its momentum

or

where p is momentum in kg*m/s, h is Planck’s constant = 6.63 x 10-34 J, and λ is the wavelength in meters

What is Planck’s constant?

Planck’s Constant is the size where quantum mechanics becomes necessary

Since "Planck's Constant" (‘h’= 6.63 x 10 - 34 Js) is such a tiny number, quantum mechanics is needed only at very small scales

An electron also has spin that is quantized in units of h.

These units (Joule-sec) are units of angular momentum

Electromagnetic Waves

Waves of energy emitted from any accelerating charges

Any object that is above absolute zero emits electromagnetic waves

The entire range of possibilities is called the “Electromagnetic Spectrum”

Still confused? Then click What are electromagnetic waves?

To learn about the wavelength of photons click to the next slide. To move onto the EM spectrum click

Electromagnetic Waves

Wavelength is :

Where,

c is the speed of light (3 x 108 m/s in a vacuum)

λ is the wavelength in meters

f is the frequency in Hertz

And

h is Planck’s constant (there it is again- do you remember its value?)

E is the energy of a photon in Joules

What is this “photon” term you’re throwing in there?

A photon is a bundle (quantum) of light

A photon has energy equal to

Recall that

h is Plank’s constant

ν is the frequency of the radiation (wave)

What does a photon do?

Both magnetic and electric forces involve the exchange of photons

The photon has zero rest mass, but has momentum, can be deflected gravity, and can exert a force

The Electromagnetic Spectrum

Think you know all about the electromagnetic spectrum? Well take a tour of the Electromagnetic Spectrum to find out more cool information. Then, if you’re brave enough, take the electromagnetic quiz. Remember to run the applet at the top of the page.

If you still need more help review the next 7 slides. If not click

TYPES OF ELECTROMAGNETIC WAVES

GAMMA RAYS

Emitted from the nuclei of atoms during radioactive decay or during high-speed collisions with particles.

Ionizing

Used in cancer treatment and for sterilization Sources: Cobalt 60, the inner core of the sun

X-RAYS

Emitted when an electron moves from certain excited states back down to its ground state, or when an electron that is moving very quickly is suddenly stopped